The B vitamins are a group of important nutrients you should include in your diet each day. If you're a woman of childbearing age, one of those B vitamins -- folate -- is especially critical.

That's because folate helps prevent certain common serious birth defects called neural tube defects, according to the National Institute of Child Health and Human Development (NICHD). Each year, about 2,000 children in the United States are born with a neural tube defect such as spina bifida, according to the March of Dimes. Getting adequate folate can reduce the risk for neural tube defects by 70 percent.

If you are a woman of childbearing age and able to become pregnant, you should get at least 400 micrograms (mcg) of folate each day. It's important to get adequate folate even before you know you're pregnant because neural tube development occurs within the first three to four weeks of pregnancy -- before many women realize they are pregnant. (The neural tube becomes the spinal cord as the fetus continues to develop.) It takes time for folate to build up in the body to a level that offers protection against neural tube defects, the NICHD says.

Although researchers aren't sure what causes neural tube defects, they do know that folate/folic acid offers protection. In spina bifida, the backbone fails to develop normally, leaving the newborn vulnerable to spinal cord disease and injury. In anencephaly, another neural tube defect, the brain and skull don't properly form, usually leading to death at birth.

Sources

Folate is a B vitamin found naturally in certain foods: dark green, leafy vegetables such as spinach and kale; navy beans; and oranges. But the typical American diet includes only about 200 mcg of folate, about half of what a woman of childbearing age needs.

A way to boost folate intake is to take a dietary supplement. Supplements contain folic acid, a synthetic form of folate.

But only about a third of women of childbearing age take a multivitamin or other dietary supplement containing 400 mcg of folic acid each day, according to the New England Journal of Medicine.

Another good source of folic acid is cereals and grains, which are now fortified with this form of folate. Some cereals -- including brands such as Total, Special K and Cap'n Crunch -- contain 400 mcg of folic acid (a full day's intake) in each serving, according to the Centers for Disease Control and Prevention. Other cereals and grains such as white flour are fortified with 140 mcg of folate per serving. Because many of the fortified foods don't contain a full day's recommended intake of folate, women of childbearing age shouldn't rely solely on foods to get their folate, the NICHD says.

Other benefits

Folate not only helps protect against birth defects, but it, along with other B vitamins, also helps control the level of the amino acid homocysteine in adults. High levels of this amino acid are associated with heart disease. It is not clear exactly what role folate plays in heart disease. Folate also helps make red blood cells, and research suggests that folate may prevent certain types of cancer, particularly colon and rectal cancer. The National Institutes of Health's Office of Dietary Supplements (ODS) recommends a daily folate intake of 400 mcg for both men and women.

Daily maximum of folate

Unlike some nutrients like vitamin A or E, folate is not toxic at high levels. But the Public Health Service recommends that total daily amount of folic acid in supplements and fortified foods not exceed 1,000 mcg. The danger is that an excess of folic acid may cover up a health condition caused by a deficiency in another B vitamin: B-12. An untreated deficiency in B-12 can lead to permanent nerve damage, according to the ODS.

Folate deficiency

Certain medical conditions and medications can increase the risk for folate deficiency. Alcoholics are at risk for this deficiency, because alcohol interferes with how the body absorbs folate, the ODS says. Alcoholics also often have poor nutrition, which makes them less likely to get adequate amounts of folate.